Project 2 - SUMMARY/ABSTRACT While surgical resection is potentially curative for early stage hepatocellular carcinoma (HCC), care of advanced stage disease is limited to treatment with sorafenib, regorafenib, or nivolumab which increase survival by 3-4 months. Even in patients who undergo resection, recurrence within 5 years occurs in ~70%. Therefore, there is an urgent need for new therapeutic strategies to treat advanced disease and to prevent postoperative recurrence. Our long-term translational goal is to improve outcomes in patients with advanced stage HCC and in post-operative HCC patients. More than 90% of HCC cases arise in the setting of hepatic injury and inflammation, which involve production of several cytokines, notably hepatocyte growth factor (HGF) and IL-6 that activate signal transducer and activator of transcription (STAT) 3. STAT3 is a master regulator of most of the key hallmarks and enablers of cancer and its activation occurs in approximately 60% of HCCs where it is a predictor of tumor recurrence and contributes to immune resistance in HCC by regulating the development, recruitment, and the immunosuppressive activity of myeloid-derived suppressor cells (MDSCs). Our group, in collaboration with a clinical-stage pharmaceutical firm (Tvardi Therapeutics, Inc.), used computer-based docking and lead-compound optimization strategies to identify TTI-101 (C188-9), a potent, non-toxic and orally bioavailable inhibitor of STAT3. Administration of TTI-101 to mice that develop liver steatosis and fibrosis followed by HCC (hepatocyte-specific Pten knockout mice) led to arrest of tumor growth, as well as marked reduction in liver injury and fibrosis. A Phase I study of patients with solid tumors, including HCC, at MD Anderson showed no toxicity through dose level (DL) 3 and resulted in a partial clinical response after two cycles at DL2 in the first HCC patient entered into the trial. Tvardi collaborated with the Department of Pathology at MD Anderson to develop a clinical laboratory improvement amendments (CLIA)-certified IHC test and score for pY-STAT3 levels by immunohistochemistry (IHC), which was further developed into a pY-STAT3 score for HCC tumors. We hypothesize that STAT3 contributes to HCC tumor growth and immune resistance, as well as HCC development in the setting of liver inflammation and fibrosis. We hypothesize further that use of a STAT3 inhibitor, such as TTI-101, will be more effective at treating advanced HCC when combined with standard therapy (nivolumab) than nivolumab alone and will prevent postoperative recurrence. In Aim 1, we will determine the safety and early effectiveness of TTI-101 when used in combination with nivolumab in patients with surgically non-resectable HCC. In Aim 2, we will determine the utility of the pY-STAT3 score of HCC patient tumors or adjacent non-tumoral liver in predicting postoperative recurrence. In Aim 3, we will determine if TTI-101 adjuvant therapy reduces HCC recurrence. The impact of this project would be increased survival of patients with advanced stage HCC and reduced recurrence of HCC in patients who undergo surgical resection.